This invention relates to the testing of precision components for miniature watch motors or the like and more particularly for measuring the concentricity of the rotor assembly of the miniature motor.
Large variations in the concentricity relationship between the outside diameter of the rotor and the axle pivots thereof will produce similar variations in the motor performance because the magnetic locking force is very sensitive to changes in the physical air gap or space between the rotor poles located at the periphery of the rotor and the magnetic biasing means utilized to stop the rotor in a predetermined position after energization of the miniature motor.
Thus, a need exists to provide an efficient and accurate test apparatus for measuring the concentricity of the rotor with respect to its axle pivots without any damaging forces being transmitted to the radial magnet material.